430 READINGS IN EVOLUTION, GENETICS, AND EUGENICS 
The factorial make-up of the various mice in Miss Durham’s 
experiments would, then, be represented as follows: 
BICP =black 
BiCP =blue (dilute black) 
bICP =chocolate (absence of black) 
biCP =silver fawn (dilute chocolate) 
The following experiments indicate the mode of heredity on the 
factorial basis: 
1. P Black (BICP) XSilver-fawn (biCP) 
F, 100 per cent Black (BICP-biC P) 
F, Black (BICP) Blue (BiCP) Chocolate (6JCP) Silver-fawn 
(biCP) 
9 3 3 I 
2. P Blue (BiCP)XChocolate (bICP) 
F, Ioo per cent Black (BiC P-bICP) 
F, Black (BICP) Blue (BiCP) Chocolate (bJCP) Silver-fawn 
(biCP) 
9 3 3 I 
3. P Blue (BiCP) XSilver-fawn (biCP) 
F, roo per cent Blue (BiC P-biCP) 
F, Blue (BiCP) Silver-fawn (biCP) 
3 I 
DIFFERENT KINDS OF ALBINOS 
Any one of the color types mentioned, if lacking in the factor C, 
will be an albino, though carrying the other factors for color. For 
example, there may be a Black-albino (BIcP), a. Blue-albino (BicP), 
a Chocolate-albino (bIcP), or a Silver-fawn-albino (bicP). 
That color factors are present in albinos may be shown by the 
following experiment. An albino had appeared in a Black stock and 
was crossed with a Silver-fawn, thus: 
4. P Silver-fawn (6iCP)XAlbino extracted from Black (BIcP) 
F, 100 per cent Black (biCP-BIcP) 
Black Blue Chocolate Albino-Black Silver-fawn 
(BICP) (BiCP) (bICP) (BIcP) (biCP) 
F 27 9 9 9 3 
*| Albino-Blue Albino-Chocolate Albino-Silver-fawn 
(BicP) (bIcP) (biCP) 
3 3 gs 
